A conventional pressure regulating device is used to regulate the input gas pressure and is disclosed in Taiwan Patent No. I230233 and generally includes a casing having an inlet which is connected to a gas source to introduce gas into the device, and an outlet for transferring pressure-regulated gas to various devices at downstream, and a regulating valve assembly which has a valve movably supported in the casing and located between an open position and a closed position. A piston assembly biases the valve to the open position when the pressure at the outlet is below a pre-set value. The piston assembly includes a pressure sensing surface which is shaped to include a long axis and a short axis. The long axis A is longer than the short axis B. The piston assembly is corresponsive to the gas pressure between the inlet and the outlet. When the pressure at the outlet is over a pre-set value, the bias pressure to the valve is reduced so as to move the valve to the closed position.
Beside the pressure regulating device to regulate the pressure of the gas, the volume of the gas is also needed, the volume regulating device is to control the volume of the gas. Taiwan Utility Model M311022 discloses a needle valve and a body of the volume regulating device, and a seal ring is located between the needle valve and the body of the volume regulating device. The needle valve of the volume regulating device includes multiple seal rings so that the machining requirement is lowered and the life of use is prolonged.
When in use, the pressure regulating device and the volume regulating device are connected by a plastic hose or a metal hose which however is easily loosened by vibration and the hose might be disconnected from the devices to shut down the whole mechanism. Furthermore, the combination of the pressure regulating device, the volume regulating device and the plastic hose or metal hose occupies too much space. If the oxygen generating machine is a medical-use device, the loosened hose could lead to a dangerous result.
The present invention intends to provide an integral volume and pressure regulating device for an oxygen generating machine so as to improve the shortcomings of the conventional ones.